Former Metropolitan Police commissioner Lord Ian Blair has died aged 72, Sky News understands.
Lord Blair led the force for three years between 2005 and 2008 and was in charge during the 7/7 London bombings.
The 20th anniversary of the attack, which killed 52 people, was on Monday.
The Met’s response notoriously including the shooting dead of an innocent man, Jean Charles de Menezes, at Stockwell Tube station two weeks later.
He was killed under the mistaken belief he was a suicide bomber.
False details about how he acted were put out by the Met, insinuating the Brazilian was in some way responsible for what happened.
Lord Blair repeated those details and was later accused of a cover-up and obstructing inquiries into the incident.
Sky News crime correspondent Martin Brunt said “it effectively blighted his time as commissioner” and that “history will probably judge him quite harshly”.
“But there were good things,” he added.
“[Lord Blair] took hold of the Met and forged a much better relationship with MI5 in the wake of the 7/7 bombings.
“Some of his big things were diversity and he reformed the way the Met recruited – people from ethnic communities.
“He was a big supporter of neighbourhood policing. Although that, over the years, dwindled due to a lack of funding. But it’s more or less the model police forces across Britain are reintroducing.”
Lord Blair was appointed commissioner by Labour but quit in late 2008 after saying he did not have the confidence of the new Tory mayor Boris Johnson.
He was seen as a liberal figure – sometimes jokingly referred to as “PC Blair” by other officers – and was active in the House of Lords right up until his death.
He joined the police in 1970s and served with other forces before joining the Met. His early work as a detective in London included investigating the fatal 1987 King’s Cross fire.
Senior positions for the Thames Valley and Surrey forces followed before he returned to the capital as deputy commissioner – and then the top job.
